This invention relates to eye patches, and in particular to occlusive patches for covering the good eye of a patient suffering from amblyopia, i.e. weak or lazy eye, for forcing the amblyopic (or bad) eye to regain full visional function.
The treatment of amblyopia by covering the good eye of a patient so as to compel the patient to use his amblyopic or bad eye is well established in ophthamology as a very effective way for treating this disorder. Amblyopia is a very common disorder among children, and despite the known effectiveness of covering the patient's good eye to correct the disorder, remains the leading cause of visual loss among children. Although the task of covering the patient's good eye would appear to be simple, in fact it has not been implemented with particularly good success. One of the obstacles to effective treatment of ambylopia remains patient and parent non-compliance with the patching process, and this non-compliance often results from problems with the patch itself.
Eye patches which are presently on the market use conventional adhesives, as are found on household adhesive tape. U.S. Pat. Nos. 4,134,401 (Galician) and 4,682,371 (Heltman) disclose eye patches having pressure sensitive adhesive strips for removably securing the patch over the user's eye, the adhesives being of the conventional contact type. U.S. Pat. No. 3,952,735 describes an eye bandage which is held in operative position by adhesive areas employing conventional adhesives. U.S. Pat. Nos. 4,331,136 (Russell et al.) and 4,635,625 (Teeple) disclose eye masks which employ adhesives for securing the device to the person's face, and these too use conventional adhesives. Thus, such conventional adhesive system have been in wide use for many years on eye patches and the like despite their well-known disadvantages; namely, tissue trauma upon removal of the adhesive device, allergic reaction to adhesive materials, the build-up of sweat under the patch which causes skin rash at the interface of the adhesive and the skin, and the ultimate failure of the adhesive, which causes the patch to fall off. Indeed, parents often report that during the summer when patching of their children's eyes would be expected to be most successful, they have to repeatedly re-apply the patch to the child. Once tissue rash or breakdown occurs, the options available to the physician for treating amblyopia become very limited, and patient frustration leads to non-compliance of the patching process and the failure of treatment of the ailment.
In view of these well-known shortcomings of the conventional adhesive systems used on eye patches, alternate patching techniques have been tried. For example, black felt patches with elastic bands ("the pirate patch") is sometimes used, but this is quite ineffective because of the ease with which the child can move the path to one side so that he can use his good eye to see around the patch. In the common situation where the child wears glasses, it is a known technique to apply tape to the lens of the glasses over the good eye, or to apply a commercial product known as the Lindener occluder to force the child to use the bad or amblyopic eye to see with. Alternatively, a technique is known whereby the lens of the good eye is reduced by a correction in the lens over that eye. However, these modifications to eye glasses are not effective because the child frequently turns his head to one side to enable him to use his good eye to see around the glasses' frame. It has been proposed to use opaque contact lenses, but this technique also has been ineffective. Indeed, one ophthamologist actually placed the cast around the head of the child to cover the good eye, only to find out later that this child could see around the cast.
Thus, even though the technique of covering the good eye of an amblyopic patient is known to be very effective in treating amblyopia, there has heretofore not been available any effective means for covering the good eye of the patient for prolonged periods to enable the patient to enjoy the benefits of this simple technique.
As discussed below, the present invention makes use of hydrocolloidal materials in conjunction with an adhesive in order to provide an eye patch which remains in place over a patient's eye. The present invention does not reside in the discovery of such hydrocolloidal materials, indeed, hydrocolloidal dressing materials have been used successfully for many years by general surgeons and internists to cover burns, pressure sores and wounds. For example, U.S. Pat. No. 3,972,328, issued Aug. 3, 1976 to J. L. Chen, discloses a medical wound dressing comprising a semi-open cell polymeric flexible foam having attached to one side a water impervious flexible polymeric film and to the other side a pressure sensitive adhesive composition. The adhesive is prepared by forming a mixture of a hydrocolloid, a rubbery elastomer, a tackifier and plasticizer. The presence of the hydrocolloid in the adhesive layer provides a material for absorbing moisture such as perspiration and wound exudate, and for transferring such moisture from the surface of the skin to the layer of the open-cell foam where it can evaporate through sides of the bandage. The foregoing Chen patent refers in turn to the following patents directed to medical dressings for removing liquid: U.S. Pat. Nos. 3,339,546, 3,122,140, 3,122,141, 3,122,142, and 3,156,242. A more recent patent disclosing another occlusive dressing having an adhesive layer with a homogeneous blend of one or more pressure sensitive adhesive materials and one or more water dispersable hydrocolloidal materials is U.S. Pat. No. 4,538,603. This patent refers to the previously cited patent to Chen, and further refers to British Patent No. 2,061,732, and U.S. Pat. Nos. 4,192,785, and 3,339,546 for disclosures of materials incorporating hydrocolloids. It is significant that all these patents which relate to any type of bandages relate to devices for covering various sorts of wounds. None of them have anything to do with covering any portion of the skin which has not been subjected to some sort of trauma which the bandage is to protect or be used in the treatment thereof. A commercial version of such wound dressing is sold under the name "DuoDERM," and is specifically stated as being used for use on small burn areas. The patents cited above are all incorporated herein by reference. As widespread as the use of wound dressings having hydrocolloidal materials used in conjunction with adhesives is, it has not heretofore occurred to ophthalomogists to apply the foregoing material to patches used for treating amblyopia. Neither internists, surgeons, and opthalomogists nor the companies that market wound dressings having hydrocolloidal materials, appear to have ever considered using such materials for occlusional therapy.